In the testing of certain devices and apparatuses, the test requires the application or provision of a linearly increasing force. In many of these circumstances, a simple compression coil spring or a spring-loaded test device can be used to provide such a linearly increasing force. However, in other situations, such as in the testing of pyro cartridges or the matching of an aerodynamic loading condition, testing requires a linearly decreasing force. Such a linearly decreasing force cannot be provided by a simple spring. The art is therefore in need of a test apparatus that can supply a linearly decreasing force.